1. Field of the Invention
The invention relates generally to a structure which provides mass transfer surface for distillation. More particularly, the invention relates to a redistribution component which can be used with catalytic distillation structure to provide enhanced separation and reaction.
2. Related Art
The concurrent reaction and separation of products from reactants has been practiced for some time, and the advantages have been recognized. Examples of the use of concurrent reaction and distillation are disclosed in U.S. Pat. Nos.:(etherification) 4,232,177; 4,307,254; 4,336,407; 4,504,687; 4,918,243; and 4,978,807; (dimerization) 4,242,530; (hydration) 4,982,022; (dissociation) 4,447,668; and (aromatic alkylation) 4,950,834 and 5,019,669.
Several different catalytic distillation structures have been proposed. See for example U.S. Pat. Nos. 4,302,356 and 4,443,559 in which a particulate catalyst is contained within the pockets on a cloth belt wound with demister wire to form a catalytic distillation structure and U.S. Pat. No. 4,731,229 which discloses a packing with corrugated elements and tape form catalyst member. In U.S. Pat. No. 5,073,236 the structures comprise two parallel gas permeable plates having the catalyst between them, are vertically placed within a column directly adjacent another pair of the plates containing the catalyst. The close packing of plates containing the catalyst when placed into the column may present too dense a catalyst bed in some instances and thus increase the residence time beyond that necessary for a given reaction.
Structures made from cloth such as fiber glass belts with pockets are wound into helix with a layer of demister wire to provide structural integrity to the resultant bale and to provide the necessary open space for a distillation. See for example U.S. Pat. No. 4,302,356. Other structures have used a plurality of layered sheets of wire with catalyst pockets bundled together. See U.S. Pat. No. 5,073,236. A final structure includes a series of mesh tubular containers for the catalyst placed horizontally across a rectangle of demister wire and then rolled into a bale as described in U.S. Pat. No. 5,431,820.
All of the present catalytic distillation structures are multicomponent. A multicomponent catalytic distillation structure may be subject to channeling of liquid and vapors and in any packed bed. The catalyst particles, even when contained within structures to provide vapor flow, tend to cause more pressure drop than the structures and thus channeling of the liquid and vapors can occur. This channeling may especially affect the reaction between two reactants one of which is a gas and the other a liquid because the channeling prevents optimum contact with the catalyst component.
Corrugated type distillation trays are known in the art. See for example U.S. Pat. Nos. 2,591,343 and 2,767,967. Both references disclose corrugated trays that have openings disposed over the entire surface of the trays, including the angled flat sides. The feature of the corrugation being covered with openings is to provide more surface area for the opening and thus better vapor-liquid contact. The trays of U.S. Pat. No. 2,767,967 were tried as replacement trays in columns for trays with downcomers.
It is a feature of the present invention that the reaction and separation characteristics of columns containing the catalytic distillation structures can be improved. The separation characteristics of a plain packed distillation column may also be improved.